From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932136AbbBSAf6 (ORCPT ); Wed, 18 Feb 2015 19:35:58 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:35818 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754273AbbBSAep (ORCPT ); Wed, 18 Feb 2015 19:34:45 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Kees Cook , Vivek Goyal , Jan Beulich , Junjie Mao , Andi Kleen , Thomas Gleixner , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 094/103] x86, boot: Skip relocs when load address unchanged Date: Wed, 18 Feb 2015 16:33:01 -0800 Message-Id: <1424305990-17983-95-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1424305990-17983-1-git-send-email-kamal@canonical.com> References: <1424305990-17983-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11-ckt16 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Kees Cook commit f285f4a21c3253887caceed493089ece17579d59 upstream. On 64-bit, relocation is not required unless the load address gets changed. Without this, relocations do unexpected things when the kernel is above 4G. Reported-by: Baoquan He Signed-off-by: Kees Cook Tested-by: Thomas D. Cc: Vivek Goyal Cc: Jan Beulich Cc: Junjie Mao Cc: Andi Kleen Link: http://lkml.kernel.org/r/20150116005146.GA4212@www.outflux.net Signed-off-by: Thomas Gleixner Signed-off-by: Kamal Mostafa --- arch/x86/boot/compressed/misc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 434f077..1b05afd 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -401,6 +401,8 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap, unsigned char *output, unsigned long output_len) { + unsigned char *output_orig = output; + real_mode = rmode; sanitize_boot_params(real_mode); @@ -439,7 +441,12 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap, debug_putstr("\nDecompressing Linux... "); decompress(input_data, input_len, NULL, NULL, output, NULL, error); parse_elf(output); - handle_relocations(output, output_len); + /* + * 32-bit always performs relocations. 64-bit relocations are only + * needed if kASLR has chosen a different load address. + */ + if (!IS_ENABLED(CONFIG_X86_64) || output != output_orig) + handle_relocations(output, output_len); debug_putstr("done.\nBooting the kernel.\n"); return; } -- 1.9.1